Fig. 4: Ribozyme-catalysed replication of a fragment of itself.
a, 3D structural model21 (left) of the TPR catalytic subunit with the γ+ segment highlighted in red. Right, sequences of the γD duplex and its constituent strands γ+ and γ−, shown with primer and triplet substrates. b, γ+ and γ− synthesis during replication of single strands and duplex. The triplets (0.2 µM each) and primers (0.1 µM each) shown in a were polymerized by the TPR (20 nM) on the indicated templates (2 nM each) in replication buffer across one or two denaturing acid cycles (polymerization: 24 h at −7 °C). Per-template yields of primer reaching full length are shown; two cycles yielded more product than a single cycle with equivalent total incubation time in ice (1 × 2 days). c, Iterative replication cycling of reactions (set-up as in b, with 0.6 mM starting KCl) with no template or 4 nM γD duplex (concentrated to ~1.8 µM in the eutectic phase). The eutectic phase concentrations of products reaching full-length were inferred from gel densitometry. Averages are shown of three independent reactions (transparent data points) set up for each cycle number. γ+ from γD template, filled red circles; γ− from γD template, open blue circles; γ+ or γ− products from no γD template, red/blue dashed crosses.
